Vererbung, Variation, Mutation. 91 



rate characters of tobacco shows that shape and size of leaf, size of stalk, and 

 leaf number are in a large measure inherited independently. The only known 

 means of producing variability as a source of new types is by crossing. But in 

 any System of tobacco breeding, quantitative characters and especially quality of 

 cured leaf are in a large measure dependant on environment. Pearl. 



225) Van Feelt, W. ? Chestnut Breeding Experience. In: Journ. of Here- 

 dity, Vol.V, Nr. 1, S. 19— 25, 1914. 



Many hybrids were obtained by crossing native species of Castanea of 

 America witn species from Europe and Asia. A great Variation in resistance to 

 bark disease was shown among the different crosses. The Asiatic chestnuts and 

 the chinquapin crosses are very susceptible to the disease. Hybrids from crosses 

 of chinquapin with the Japanese chestnut [Castanea crenata) show much improve- 

 ment over native chinquapins. The nuts are midway in size between those of 

 the parents and the quality of the fruit is excellent, although not quite equal 

 to the wild chinquapin. In maturity and blight resistant qualities it seems to 

 combine all the good characteristics of both ancestors. Pearl. 



226) EmerSOll, R. A. ? The inheritance of a recurring somatic Varia- 

 tion in variegated ears of maize. In: Amer. Natur., Bd. 48, Heft 2, S. 87 

 —115, 1914. 



The writer first recounts the experiments of de Vries on a variety of ^4«- 

 tirrhinwm with striped flowers, in which it was found that a striped plant gave 

 offspring about 90% of which bore striped flowers and 10% red flowers. 

 Both types gave in later generations plants with striped and plants with red 

 flowers, the predominating type corresponding to that of the parent plant. Cor- 

 rens also showed that a variegated plant of Miräbilis jalapa produced from a 

 variegated branch mostly plants of the same kind, while a green branch gave 

 75% off spring green to 25% variegated. 



The results of the study of red variegated ears of maize and their inheri- 

 tance are then given. They are in harmony with previous results of Hartley 

 and of East and Hayes, and though too extensive to summarize, a few of the 

 conclusions may be quoted. It was found that "the more red there is in the 

 seed planted, the larger the percentage of red ears in the progeny". Another 

 conclusion is that "the F 1 red ears arising from self-pollinated, heterogyzous, 

 variegated-eared plants behave in some cases as if they were hybrids between 

 red-eared and variegated-eared races, and in other cases as if they were hybrids 

 between red-eared and white-eared races". Emerson attributes the origin of 

 plants with varying amounts of red, to somatic variations occurring at different 

 stages in the development of the embryo or plant, in which certain cells which 

 are homogyzous for variegation (VV) become VS, i. e. with one V factor chan- 

 ged to a factor for self-colour. Germ cells descended from such a VS cell will 

 produce gametes of two kinds in equal numbers. This conception is based 

 partly on the fact that variegated-eared plants do not throw reds and whites, but 

 reds and variegates usually. There is at present no Suggestion concerning the 

 nature or cause of this germinal change from the VV to the VS condition. 



Gates. 



227) Richardson, C. W., A preliminary note on the genetics of Fr a- 

 garia. In: Journ. of Genetics, Bd. 3, Nr. 3, S. 171 — 178, 1 plate, 1914. 



In the wild F. vesca runner-production, red-fruit, and trifoliate leaves are 

 Mendelian dominants to absence of runners, white fruit and monophyllic leaves. 



